Azimo, the U.K. money transfer startup backed by Rakuten, is rolling out a neat new feature that makes it a lot easier to send money through the app and should add additional network effects to help the London-based fintech company grow. Specifically, the new functionality enables Azimo users to request, send and receive cash internationally using a mobile phone number.

The new feature is similar to something like PayPal’s Venmo mobile app for sending money to friends or Barclays Pingit, both of which let you send money with just a phone number, but in Azimo’s case it is targeting international/remittance payments.

The way it works is as follows: The sender chooses one of their phone contacts via the Azimo app to whom they want to send money. The recipient will then receive an SMS text message with a link to download and register with the Azimo app, if they haven’t already, and claim the money.

Crucially, the onus is on the receiver not the sender to input recipient bank account details or IBAN numbers, which, when you think about, is how it should be and will cut down significantly on the likelihood of a mistake being made. That in itself removes a lot of the friction involved when sending money abroad and is a workflow Azimo first played with when it let you send money via a Facebook app all the way back in 2013.

Perhaps more significantly for the company’s growth, however, Azimo’s new send via mobile number feature builds much-needed virality into the app. That’s because when you install Azimo it asks for permission to access your phone’s contacts, essentially turning the money transfer service into a payments-based social network, in the same way apps like WhatsApp do for messaging. By tying remittance to the social graph of your mobile phone it turns anyone in your phone’s contacts into a potential Azimo recipient and user.

In a call, Azimo co-founder and CEO Michael Kent, agreed with me that the new feature gives the app a network effects boost, which he noted is something VCs are fond of. He also says that once you get users used to sending money via mobile they tend to use Azimo more often, sending smaller amounts that add up to a greater amount transferred per month in total. This can been seen in Azimo’s early testing of the pay-by-mobile number functionality internally. “We ate our own dog food,” says Kent.

He also tells me the company could bring the feature to Facebook Messenger or other messaging apps, rather than relying solely on SMS, and will likely do so. However, for now he decided that since SMS is universal it was the best way to start rolling out the concept.

To that end, the new feature isn’t initially available in all 190 or so countries Azimo serves, but sees the U.K. and most of the Eurozone targeted first, as well as a more restricted launch in Poland, U.S. and Canada.

Adds Kent: “Across the UK and Eurozone, customers have access to the full functionality to send, request and receive money. We’ve rolled out a more limited function across Poland, U.S and Canada so that customers there can request and receive money from friends/family in U.K and Eurozone. This is just for our initial launch. The team are already working on adding more markets — we expect the big remittance markets India, Philippines, China and Nigeria to be turned on in the coming months.”